Qt Multimedia : How to convert/re-encode a video file

I would like to be able, using Qt Multimedia, to convert a video or audio file to another container/codec format, meaning re-encode the file.

Could someone please indicate whether this can be accomplished, and if yes, how ?
A link to an example will be wonderful.

As a related question, I suppose that for listing the video & audio codecs that are available for encoding, one would use the functions QMediaRecorder::supportedAudioCodecs and QMediaRecorder::supportedVideoCodecs. Is that correct ?

I mean that QtMultimedia is not the right tool to do video conversion.

On Linux Qt uses gstreamer as backend.

But again, converting video files from different formats in different formats is currently not something you should try to do with QtMultimedia. It uses what the OS provides and depending on your target (I'm guessing Linux) you won't have all the codecs you may need/want. Using FFMPEG, you have the Swiss Army Knife of video converter. Or if you are used to gstreamer, there also the QtGStreamer module that might be of interest.

This should work also on Windows, where GStreamer is available and working.
The hint of QtGStreamer was useful, but the problem is that it is not part of the Qt release, so at least for Windows I'll have to compile it and fix myself all problems.